By Andrew Higgins and Andrew E. KramerNew York Times
February 23, 2014

KIEV — Abandoned by his own guards and reviled across the Ukrainian capital but still determined to recover his shredded authority, President Viktor Yanukovych fled Kiev on Saturday to denounce what he called a violent coup.

Yanukovych’s official residence, his vast, colonnaded office complex, and other once-impregnable centers of power fell without a fight to throngs of joyous citizens stunned by their triumph.

As Yanukovych’s nemesis, former prime minister Yulia V. Tymoshenko, was released from a penitentiary hospital, Parliament found the president unable to fulfill his duties and exercised its constitutional powers to set an election for May 25 to select his replacement.

Hours after her release, Tymoshenko appeared before an ecstatic crowd of about 50,000 supporters at the protest encampment in Kiev, the Associated Press reported.

Speaking from a wheelchair because of back problems she suffered during 2½ years in prison, Tymoshenko praised the demonstrators killed in violence last week and urged the protesters to keep occupying the square.

‘‘You are heroes; you are the best thing in Ukraine!’’ she said of those killed. The Health Ministry on Saturday said the death toll in clashes between protesters and police had reached 82, the AP said.

Lawmakers have not decided on interim leadership. And with both Yanukovych and his Russian patrons speaking of a coup carried out by “bandits” and “hooligans,” it was far from clear that the lightning-quick events were the last act in a struggle that has not just convulsed Ukraine but expanded into an East-West confrontation.

In the capital, protesters carrying clubs and some wearing masks were in control of the entryways to the presidential palace Saturday morning and watched as thousands of citizens strolled through the grounds, gazing in wonder at the mansions, zoo, golf course, and enclosure for rare pheasants, set in a birch forest on a bluff soaring above the Dnieper River.

“This commences a new life for Ukraine,” said Roman Dakus, a protester-turned-guard, who was wearing a ski helmet and carrying a length of pipe as he blocked a doorway at the palace. “This is only a start,” he added. “We need now to make a new structure and a new system, a foundation for our future, with rights for everybody, and we need to investigate who ordered the violence.”

Yanukovych surfaced on television Saturday afternoon, apparently from the eastern city of Kharkiv, near Ukraine’s eastern border with Russia, saying he had been forced to leave the capital because of a “coup.”

He said he had not resigned and said his car had been fired upon as he drove away. “I don’t plan to leave the country. I don’t plan to resign,” he said. “I am a legitimately elected president.”

Yanukovych added: “What is happening today, mostly, it is vandalism, banditism and a coup d’état. This is my assessment, and I am deeply convinced of this. I will remain on the territory of Ukraine.”

He said he was traveling to the southeastern part of Ukraine to talk to his supporters — a plan that carried potentially ominous overtones, in that the southeast is the location, among other things, of the Crimea, the historically Russian section of the country that is the site of a Russian naval base.

The president’s departure from Kiev, just a day after a peace deal with the opposition that he had hoped would keep him in office until at least December, climaxed three months of streets protests and a week of deadly violence in Kiev. It turned what began in November as a street protest driven by pro-Europe chants and nationalist songs into a momentous but still ill-defined revolution.

With nobody clearly in charge, other than the so far remarkably disciplined fighting squads set up to protect a protest encampment in Independence Square, the Ukrainian capital and even the whole country faced a potentially dangerous power vacuum.

Adding to the combustible mix was uncertainty over the intentions of Russia, which now faces the loss of a key ally in a former Soviet republic and the prospect of a new government led by people it scorned as terrorists and fascists in what it considers a critical part of its own sphere of influence.

Tymoshenko, who was jailed by Yanukovych after losing the presidential election in 2010, was released Saturday evening from the penitentiary hospital in eastern Ukraine where she had been held, her representatives said.

Many Ukrainians — and virtually all of the pro-Western protesters — believe her conviction was politically motivated and regard her as something of a martyr to their cause.

She is widely expected to run for president in the coming election.

With security officers having disappeared from the streets, protesters claimed to have established control over Kiev.

By Saturday morning they had secured key intersections of the city and the government district of the capital, which riot police officers had fled, leaving behind burned military trucks, mattresses, and heaps of garbage at the positions they had occupied for months. There was no sign of looting, either in the city or in the presidential compound.

In Parliament, members of the opposition began laying the groundwork for a change in leadership, electing Oleksander Turchynov, an ally of Tymoshenko, as speaker.

Underscoring the volatility of the situation and the potential power vacuum, Oleg Tyagnibok, the leader of the nationalist Svoboda party, asked the country’s interior minister and “forces on the side of the people” to patrol the capital to prevent looting.

Russia, which joined France, Germany, and Poland in mediating the pact Yanukovych and opposition leaders reached Friday, introduced added uncertainty by declining to sign the accord, which reduced the power of Yanukovych.

This stirred fears that Moscow might work to undo the deal through economic and other pressures, as it did last year to subvert a proposed trade deal between Ukraine and the European Union.